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Tissue mechanical anisotropy has been shown to be diagnostically relevant in numerous clinical applications. Anisotropy can be assessed using acoustic radiation force-based techniques, including Acoustic Radiation Force Impulse (ARFI) and Viscoelastic Response (VisR) ultrasound. In this work, ARFI peak displacement (PD), as well as VisR relative elasticity (RE) and relative viscosity (RV), were implemented...
While skeletal muscle is often assumed to be structurally transversely isotropic (TI), its mechanical anisotropy is not well characterized in vivo. VisR ultrasound, a technique that provides information about the viscoelastic mechanical response of tissue, can be used for such in vivo characterization. Specifically, VisR-derived Relative Elasticity (RE) provides directionally dependent information...
Previous work has shown that the degree of anisotropy in tissue can be assessed using Acoustic Radiation Force Impulse (ARFI) imaging performed with a geometrically asymmetric excitation. In this work, we investigate the clinical relevance of mechanical anisotropy in Duchenne muscular dystrophy (DMD). Anisotropy assessment was performed using relative elasticity (RE) and relative viscosity (RV) parameters...
While skeletal muscle is often assumed to be structurally transversely isotropic, its mechanical anisotropy is not well characterized in vivo. Such in vivo characterization can be achieved using VisR ultrasound, a technique that provides information about the viscoelastic mechanical response of tissue. Specifically, VisR-derived Relative Elasticity (RE) provides directionally dependent information...
Recently, ultrasound imaging of muscle contractions has been used by several research groups to infer volitional motor intent of the user, and has shown promise as a novel muscle computer interface. Learning spatiotemporal features from ultrasound image sequences is challenging because of deformations introduced by probe repositioning. The image features are sensitive to probe placement and even small...
Early detection of pathological processes is crucial for the prognosis and treatment of patients, which can be facilitated through studying tissue biomechanical properties. Shear wave elastography is a technique to estimate the shear modulus of tissue. Such measurements quantify elasticity linearized around an immediate state of local stress condition, under applied nature of excitation. Stress-strain...
Ultrasound velocity in soft biological tissues is defined by the molecular composition of the tissues [1]. Water is the main molecular component of soft tissues and muscle water content is typically over 70%. Ultrasound velocity in muscle is a linear function of the water content [2]. Since the muscle is the main water reservoir of human body, measurements of ultrasound velocity in muscle may serve...
Neck pain is a common occupational health complaint associated with exposure to repetitive loads and vibrations. Currently there are no methods to measure the dynamic motion of the cervical spine in at-risk individuals in the work environment. The aim of the current study is to develop a methodology for calculating real-time in-vivo C4-5-6 functional spinal unit (FSU) kinematics by co-registering...
In fascioscapulohumeral muscular dystrophy (FSHD) and many other neuromuscular disorders there is a need for biomarkers to diagnose, quantify and longitudinally follow muscle disease. Furthermore, the pathophysiological mechanisms leading to muscle weakness in most neuromuscular disorders are not completely understood. Speckle tracking allows to quantify muscle deformation. This dynamic information...
Attenuation in the skeletal muscle microvascular response to insulin plays a critical role in type 2 diabetes and obesity-induced insulin resistance. The goal of the project detailed in this paper was to evaluate the use of super-resolution ultrasound (SR-US) imaging for performing a quantitative analysis of insulin-mediated microvascular changes in skeletal muscle. An Acuson Sequoia 512 ultrasound...
Patients with chronic heart failure have reduced cardiac output and capacity for exercise-induced capillary vasodilation. Clinicians use left ventricular assist device (LVAD) therapy to improve physical function, but LVAD devices are designed to provide continuous blood flow and cannot increase blood flow in response to demand (i.e., exercise). Hence, this study investigated whether skeletal muscle...
In Duchenne muscular dystrophy (DMD), muscle fiber necrosis and subsequent progressive replacement of muscle by fibrous tissue and fat impacts the degree of anisotropy (DoA) in mechanical properties. Mechanical DoA can be assessed in skeletal muscle using Viscoelastic Response (VisR) ultrasound. We hypothesize that in vivo VisR DoA measures in the rectus femoris (RF) muscles of boys with DMD statistically...
Approximately 15 million people experience a stroke each year worldwide and two-thirds of these individuals require rehabilitation. Post-stroke spasticity is one of the common consequences characterized by excessive muscle tone resulting in an increase of muscle stiffness. To date, the assessment of spasticity is still a lack of gold standards. We prospectively evaluated the feasibility of ultrasound...
The assessment of post-stroke muscle spasticity is challenging due to lack of a gold standard. The Modified Ashworth Scale (MAS), commonly used in evaluating spasticity is neither quantitative or reliable. We have reported the use of ultrasound strain imaging (USI) to assess rigid biceps brachii muscle (BBM) in Parkinson's disease [1]. We have now extended the application of USI to determining spastic...
Myofascial trigger points (MTrPs) are palpable painful nodules that can develop in skeletal muscle and are associated with myofascial pain syndrome (MPS), a common chronic pain condition. Symptomatic MTrPs are often a therapeutic target for management of MPS, but the pathophysiology of MTrPs are poorly understood, and the diagnostic criteria lack reliability. Based on the results of our previous studies...
Evaluation of rheological behavior of soft tissues provides an important diagnosis tool. Nowadays, most of the available commercial ultrasound systems assume tissues as isotropic and purely elastic. Recently in order to fully characterize the rheological behavior of tissues, methods to estimate both shear wave speed (V) and attenuation (α) were developed for isotropic media [1, 2]. In acoustic radiation...
Preclinical studies have shown that MRI-guided focused ultrasound (MRgFUS) can achieve spatially localized thermal exposures in the range of 41–43°C. This presents an advantageous scenario for a plethora of targeted therapeutics. It has been observed that the administration of contrast agent microbubbles (MB) can facilitate increases in temperature with focused ultrasound (FUS), resulting in accelerated...
Chronic and advanced heart failure patients experience reduced capacity for exercise, likely due to reduced cardiac output and exercise-induced capillary vasodilation. To address these symptoms, clinicians implant a left ventricular assist device (LVAD) to improve physical function for this patient population. However, most LVADs, including the HeartMateII investigated in this study, are designed...
Recently, ultrasound imaging of muscle contractions has been used by several research groups to infer volitional motor intent of the user, and has shown promise as a novel muscle computer interface. Learning spatiotemporal features from ultrasound image sequences is challenging because of deformations introduced by probe repositioning. The image features are sensitive to probe placement and even small...
Ultrasound imaging, as a non-invasive method which can recognize morphological changes of forearm muscles, has been gradually applied in the field of gesture recognition. In this paper, we proposed a B-mode ultrasound-based gesture database to provide a standard platform for the evaluation of different gesture recognition algorithms. The ultrasonic signals of the forearm according to the preset paradigm,...
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